The present invention relates to a recording and reproducing system for recording digital data including audio visual data, such as digital image data and sound data, and computer data, in a disk storage medium, and reproducing digital information from the disk storage medium, and also to a data recording and reproducing method applied to the system.
This application is based on Japanese Patent Applications No. P09-338760 filed on Dec. 9, 1997 and No. P09-341385 filed on Dec. 11, 1997, the contents of which are incorporated herein by reference.
In recent years, recording and reproducing systems have been developed, which record and reproduce "multimedia data", such as digital image data (including static image) and sound data. In particular, a DVD drive, using a DVD (Digital Versatile Disk) as a storage medium, has attracted public attention. The DVD drives include DVD-ROM drives, only for use in reproduction, and DVD-RAM drives for use in both record and reproduction. Stream data consisting of serial data, including image data and sound data, is hereinafter referred to as AV (Audio Visual) data.
A DVD-RAM drive has functions of not only reproducing AV data stored in a DVD but also recording AV data transmitted from a digital broadcast station or data output from a personal computer. For this reason, the DVD-RAM drive is particularly known as an external storage device of a personal computer, as well as a video player or video deck for reproducing AV data on the screen of a television receiver. Moreover, the DVD-RAM drive is expected to be used in future as a memory medium incorporated in a set top box or IRD (Integrated Receiver Decoder), which has a receiver including, for example, a digital satellite broad-casting antenna and having a function of displaying received digital AV data on a television receiver or a display of a personal computer.
The disk storage medium used in such a DVD-RAM drive requires high reliability, particularly when it is used as an external storage medium of a personal computer. This is because, if data write error or data read error occurs in the disk storage medium, the computer may not normally operate. To improve the reliability of the disk storage medium, a defect managing system is employed, in which a spare area is prepared in advance in the disk storage medium, and if a defect area where data write error occurs exists, data is written in the spare area.
In this defect managing system, an address of a physical block corresponding to a defective block is changed to the address of a substitute block in an address conversion table representing the relationship between a logical block, i.e., an access unit (a management unit in the host system) and a physical block (a physical storage area on the disk storage medium).
When a controller (CPU) of the DVD-RAM drive accesses a logical block access-requested by the host system, it obtains a physical block corresponding to the logical block by means of the address conversion table, so that data can be recorded or reproduced. If the physical block is a defective block, the address of a substitute block to be substituted for the defective block is registered. Therefore, if the CPU is to access data stored in the defective block, it accesses the substitute block.
Data treated by a personal computer (hereinafter referred to as CP data) can be treated in units of logical block. If a defect occurs in a block, the drive actually accesses a substitute block. Although the access operation is not continuous for this reason, this does not cause a significant problem. However, in a recording and reproducing system for recording and reproducing AV data, AV data must be treated as serial data (stream data). In the conventional defect managing system, a substitute block is used in the case where a defect occurs in a block. Therefore, when AV data is serially reproduced, data (not necessarily formed in units of stream) which should have been recorded in a defective block is read and reproduced from the substitute block. For this reason, in the process of reproducing AV data, when the object of the access operation is changed from continues physical blocks to the substitute block, it is highly possible that the reproduction of AV data is temporarily interrupted. In other words, in a recording and reproducing system which treats a plurality of kinds of data, such as CP data and AV data consisting of serial data, if the conventional defect managing system is simply applied, problems may arise particularly in the data reproduction process.
Further, when a read error in a reading process or a write error in a write process occurs in a physical block to be accessed, it is not necessarily be caused by a defect in the physical block itself on a disk storage but may result from dust adhered on the medium. In particular, in case of a DVD-RAM drive, since the DVD is an exchangeable disk storage medium which is not fixed in the drive, unnecessary substance such as dust may be easily adhered to the disk storage medium by insertion/removal of the medium in/from the drive. In case where the write error or read error is caused by unnecessary substance, e.g., dust, a normal writing or reading process can be executed if the unnecessary substance is removed. Thus, such an error is not a nonrecoverable error. The unnecessary. substance, e.g., dust, adhered on the disk storage medium is often removed naturally from the disk storage medium by repeated data recording and reproducing operation of the drive. However, according to the conventional defect managing system, even if the physical block itself is not a defective block, if a write error occurs, the physical block is unusable and a substitute block in the spare area is used instead. Therefore, a great deal of the spare area is used, and a normal physical block, which is not defective, is liable to be wasted. In case of a read error, since a retry process is generally executed a plurality of times, there is high possibility of the unnecessary substance such as dust being removed at that process.